Electric motor driven lubrication supply system shutdown system and method

ABSTRACT

A system and method for controlling lubricant displacement from a lubrication system and a rotating machine includes supplying a gaseous fluid to the lubrication supply system to displace the lubricant. The gaseous fluid is preferentially directed through a first section of the lubrication supply system and to the rotating machine, and is at least inhibited from flowing through a second section of the lubrication supply system. As a result, the gaseous fluid displaces the lubricant in the rotating machine and in the first section of the lubrication supply system, while the second section of the lubrication supply system remains at least substantially full of lubricant.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

This invention was made with Government support under Contract No.N00019-02-C-3002, awarded by the U.S. Navy. The Government has certainrights in this invention.

TECHNICAL FIELD

The present invention relates to rotating machine lubrication and, moreparticularly, to a system and method for controlling lubricant removalfrom the rotating machine and the machine lubrication supply systemduring shutdown of the machine.

BACKGROUND

Many aircraft gas turbine engines are supplied with lubricant from apump driven lubrication supply system. In particular, the lubricationsupply pump, which may be part of a pump assembly having a plurality ofsupply pumps on a common, engine-driven or electric motor driven shaft,draws lubricant from a lubricant reservoir, and increases the pressureof the lubricant. The lubricant is then delivered, via an appropriatepiping circuit, to the engine. The lubricant is directed, viaappropriate flow circuits within the engine, to the various componentsthat may need lubrication, and is collected in one or more recoverysumps in the engine. One or more of the pump assembly pumps then drawsthe lubricant that collects in the recovery sumps and returns thelubricant back to the reservoir.

When an aircraft gas turbine engine is shutdown, the lubricant istypically removed and returned to the reservoir to reduce the viscousdrag due to residual lubricant on rolling and sliding lubricatedsurfaces during a subsequent startup. In many instances this isaccomplished by actuating a valve that, when appropriately positioned,allows the supply pumps to draw air, rather than lubricant, into thesystem. The supply pumps direct the air into the supply system andengine, displacing the lubricant therefrom, and directing the displacedlubricant back to the lubricant reservoir.

Although the above-described systems and methods are generally safe,reliable, and robust, theses systems and methods do suffer certaindrawbacks. For example, during a subsequent cold engine and lubricationsystem startup, after the lubricant has been removed from thelubrication system and engine, the lubrication system and engine arefirst refilled with lubricant before lubricant pressure risessufficiently to force lubricant into some engine components. Becauselubricant is removed from the entire lubrication system during theengine shutdown sequence, the subsequent startup can use an undesiredamount of power and take an undesired amount of time to raise lubricantpressure sufficiently high.

Hence, there is a need for lubricant supply system and method that canremove lubricant from a rotating machine during shutdown of the machineand supply system, while decreasing the amount of power and time neededto raise lubricant pressure during a subsequent startup of the supplysystem and machine. The present invention addresses at least this need.

BRIEF SUMMARY

In one embodiment, and by way of example only, an aircraft lubricationsupply system includes a motor, a pump, a fluid supply line, a fluidbypass line, and a controller. The motor is coupled to be selectivelyenergized from a power bus and is operable, upon being energized, torotate at a rotational speed and supply a drive force. The pump has atleast a fluid inlet and a fluid outlet, is coupled to receive the driveforce from the motor and is configured, in response thereto, to drawfluid into the fluid inlet from either a lubricant source or a gaseousfluid source, and to discharge the fluid via the fluid outlet. The fluidsupply line is coupled to the fluid outlet and is configured to supplythe fluid discharged from the fluid outlet to a rotating machine. Thefluid bypass line has an inlet and an outlet. The fluid bypass lineinlet is coupled to the fluid supply line at a first location, and thefluid bypass line outlet is coupled to the fluid supply line at a secondlocation that is downstream of the first location. The bypass controlvalve is disposed between the fluid bypass line inlet and the fluidbypass line outlet, and is operable to control fluid flow at leastthrough the fluid bypass line. The controller is configured to couple tothe power bus and to receive a machine de-lube signal that indicates therotating machine is being de-lubricated. The controller is operable,upon receipt of the machine de-lube signal, to controllably energize themotor from the power bus to thereby displace at least a substantialvolume of lubricant in the fluid supply line and the rotating machinewith fluid from the gaseous fluid source, and to cause the bypasscontrol valve to move to a position that results in the fluid bypassline remaining at least substantially full of lubricant when the atleast substantial volume of lubricant is displaced from the fluid supplyline and the rotating machine.

In another exemplary embodiment, a method of removing lubricant from alubrication supply system and a rotating machine supplied with lubricantby the lubrication supply system includes supplying a gaseous fluid tothe lubrication supply system to displace the lubricant. The gaseousfluid is preferentially directed through a first section of thelubrication supply system and to the rotating machine, and is at leastinhibited from flowing through a second section of the lubricationsupply system. As a result, the gaseous fluid displaces the lubricant inthe rotating machine and in the first section of the lubrication supplysystem, while the second section of the lubrication supply systemremains at least substantially full of lubricant.

Other independent features and advantages of the preferred lubricationsupply system and method will become apparent from the followingdetailed description, taken in conjunction with the accompanyingdrawings which illustrate, by way of example, the principles of theinvention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1, which is the sole FIGURE, is a schematic diagram of an aircraftlubrication supply system according to an exemplary embodiment of thepresent invention.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT

The following detailed description is merely exemplary in nature and isnot intended to limit the invention or its application and uses.Furthermore, there is no intention to be bound by any theory presentedin the preceding background or the following detailed description. Inthis regard, although the system is depicted and described as supplyinglubricant to a turbomachine, it will be appreciated that the inventionis not so limited, and that the system and method described herein maybe used to supply lubricant to any one of numerous airframe mountedrotating machines.

The following detailed description is merely exemplary in nature and isnot intended to limit the invention or its application and uses.Furthermore, there is no intention to be bound by any theory presentedin the preceding background or the following detailed description. Inthis regard, although the system is depicted and described as supplyinglubricant to a turbomachine, it will be appreciated that the inventionis not so limited, and that the system and method described herein maybe used to supply lubricant to any one of numerous airframe mountedrotating machines.

With reference now to FIG. 1, a schematic diagram of an exemplaryaircraft lubrication supply system 100 is depicted, and includes areservoir 102, a pump assembly 104, a motor 106, and a controller 108.The reservoir 102 is used to store a supply of lubricant 112 such as,for example, oil or other suitable hydraulic fluid. A level sensor 114and a temperature sensor 116 are installed within, or on, the reservoir102. The level sensor 114 senses the level of lubricant in the reservoir102 and supplies a level signal representative of the sensed level tothe controller 108. The temperature sensor 116 senses the temperature ofthe lubricant in the reservoir 102 and supplies a temperature signalrepresentative of the sensed temperature to the controller 108. It willbe appreciated that the level sensor 114 and the temperature sensor 116may be implemented using any one of numerous types of level andtemperature sensors, respectively, that are known now or that may bedeveloped in the future.

The pump assembly 104, at least in n the depicted embodiment, includes aplurality of supply pumps 118 and a plurality of return pumps 122. Thesupply pumps 118 each include a fluid inlet 117 and a fluid outlet 119.The supply pumps 118, when driven, draw fluid from one of two fluidsources, and discharge the fluid, at an increased pressure, into a fluidsupply conduit 124. The fluid supply conduit 124, among other potentialfunctions, supplies the lubricant to one or more rotating machines.Although one or more various types of machines could be supplied withthe lubricant, in the depicted embodiment the lubricant is supplied to arotating turbomachine. It will be appreciated that each of the pumps118, 122 that comprise the pump assembly 104 could be implemented as anyone of numerous types of centrifugal or positive displacement typepumps, but in the preferred embodiment each pump 118, 122 is implementedas a positive displacement pump.

The two fluid sources from which the supply pumps 118 may draw fluidinclude the reservoir 102 and a gaseous fluid source 126. The gaseousfluid source 126 may be configured as any one of numerous sources ofgaseous fluid, but in the depicted embodiment it is configured as an airsource. Preferably, the surrounding environment acts as a suitable airsource. If not, however, a dedicated source of a suitable gas may beused. The specific source from whence the supply pumps 118 draw fluidmay be controlled by, for example, a de-lube control valve 128. It willbe appreciated that the de-lube control valve 128 may be implementedusing any one of numerous types of valves to. In the depictedembodiment, however, the de-lube control valve 128 is implemented as asolenoid-operated valve.

As FIG. 1 also depicts, a lubricant filter 132 may also be disposedwithin the lubricant supply conduit 124. The lubricant filter 132removes any particulate or other debris that may be present in lubricantbefore it is supplied to the rotating machine. A filter bypass valve134, and appropriate bypass piping 136, are disposed in parallel withthe lubricant filter 132. The bypass valve 134 is configured such thatit is normally in a closed position, and moves to the open position whena predetermined differential pressure exists across it. Thus, if thelubricant filter 132 becomes clogged and generates a sufficiently highdifferential pressure, the bypass valve 134 will open to ensure asufficient flow of lubricant to the rotating machine is maintained.

The lubricant supply conduit 132 also includes a pair of pressuresensors, a filter inlet pressure sensor 138 and a filter outlet pressuresensor 142. The pressure sensors 138, 142 are each operable to senselubricant pressure and to supply a pressure signal representative of thesensed pressure to the controller 108. As the assigned nomenclatureconnotes, the filter inlet pressure sensor 138 senses lubricant pressureat the inlet to the lubricant filter 132, and the filter outlet pressuresensor 142 senses lubricant pressure at the outlet of the lubricantfilter 132. It will be appreciated that the depicted configuration ismerely exemplary of a particular embodiment, and that the system 100could be implemented with more or less than this number of pressuresensors. For example, the system 100 could be implemented with only thefilter inlet pressure sensor 138 or only the filter outlet pressuresensor 142, with a plurality of filter inlet pressures sensors 138 andfilter outlet pressure sensors 142, or with no pressure sensors.

The temperature of the lubricant that is supplied to the rotatingmachine is controlled, at least partially, via a fluid bypass line 144and a bypass control valve 146. The fluid bypass line 144 includes aninlet 148 and an outlet 152. The fluid bypass line inlet 148 is coupledto the fluid supply line 124 at a first location, and the fluid bypassline outlet 152 is coupled to the fluid supply line 124 at a secondlocation downstream of the first location. A heat exchanger 154 isdisposed in the fluid bypass line 144. Fluid in the bypass line 144 andfluid from a second fluid system 175 flow into and through the heatexchanger 154. In the heat exchanger 154, heat is transferred betweenthe two fluids. During normal system 100 operation, heat is typicallytransferred from the fluid (e.g., lubricant) in the fluid bypass line144 to the fluid from the second fluid system 175, thereby cooling thefluid in the fluid bypass line 144. The cooled fluid then flows backinto the fluid supply line 124. The amount of fluid (if any) that flowsinto and through the fluid bypass line 144 is controlled via the bypasscontrol valve 146, embodiments of which will now be briefly described.

The bypass control valve 146 is disposed in the fluid supply line 124between the fluid bypass line inlet 148 and the fluid bypass line outlet152. The bypass control valve 146 is operable to control fluid flow atleast through the fluid bypass line 144. More specifically, in thedepicted embodiment, the bypass control valve 146 is movable between aclosed position and an open position. When the bypass control valve 146is in the closed position, all of the fluid discharged from the supplypumps 118 will flow into and through the fluid bypass line 144.Conversely, when the bypass control valve 146 is in the open position,most (if not all) of the fluid discharged from the supply pumps 118 willflow through the bypass control valve 146, and only a portion (if any)of the fluid will flow into and through the fluid bypass line 144.

From the above discussion, it may thus be appreciated that during normalsystem operations the bypass control valve 146 is preferably positionedto regulate the temperature of the lubricant supplied to the rotatingmachine. That is, if the lubricant discharged from the supply pumps 118is below a predetermined temperature, then the bypass control valve 146will be open and only a portion (if any) of the discharged lubricantdischarged will flow into and through the fluid bypass line 144. If,however, the lubricant discharged from the supply pumps 118 reaches orexceeds a predetermined set temperature, then the bypass control valve146 will close and all of the fluid discharged from the supply pumps 118will flow into and through the fluid bypass line 144, and be cooled inthe heat exchanger 154.

Before proceeding further it is noted that the bypass control valve 146may be variously disposed and variously configured. For example, and asis depicted in phantom in FIG. 1, rather than being disposed in thesupply line 124, the bypass control valve 146 could be disposed in thefluid bypass line 144. Moreover, the bypass control valve 146 could beimplemented using any one of numerous suitable devices, and beconfigured to move between the closed and open positions based onvarious sensed temperatures. For example, in the depicted embodiment thebypass control valve 146 is implemented using a thermally actuatedvalve, such as a eutectic-based actuator operated valve, that moves avalve element between the closed and open position based on thetemperature of the actuator. With this type of valve, the actuatortemperature varies with fluid temperature at the outlet of the bypasscontrol valve 146 and, based on this temperature, controls the positionof the valve element. In other embodiments, the fluid temperature at theinlet of the bypass control valve 146 could be used. In addition, afluid temperature sensor could be included to sense fluid temperature atone or more locations in the fluid supply line 124 and the sensedtemperature could be used to control an electric, hydraulic, orpneumatic actuator, or various other actuator types, to move the bypasscontrol valve 146 between the closed and open positions.

No matter the specific configuration of the bypass control valve 146, itis noted that the lubricant that is ultimately supplied to the rotatingmachine flows to various components within the machine and is collectedin one or more sumps in the rotating machine. The lubricant that iscollected in the rotating machine sumps is then returned to thereservoir 102 for reuse. To do so, a plurality of the above-mentionedreturn pumps 122 draws used lubricant from the rotating machine sumpsand discharges the used lubricant back into the reservoir 102 for reuse.It will be appreciated that the configuration of the pump assembly 104described herein is merely exemplary, and that the pump assembly 104could be implemented using any one of numerous other configurations. Forexample, the pump assembly 104 could be implemented with a single supplypump 118 and a single return pump 122, or with just one or more supplypumps 118. No matter how many supply or return pumps 118, 122 are usedto implement the pump assembly 104, it is seen that each pump 118, 122is mounted on a common pump assembly shaft 148 and is driven via a driveforce supplied from the motor 106.

The motor 106 is selectively energized from a power bus 115 and, whenenergized, rotates at a speed controlled by the controller 108 tothereby supply the drive force to the pump assembly 104. In the depictedembodiment the motor 106 is directly coupled to the pump shaft 148 andthus rotates the pump shaft 148 (and thus the pumps 118, 122) at themotor speed. It will be appreciated, however, that the motor 106, ifneeded or desired, could be coupled to the pump shaft 148 via one ormore gear assemblies, which could be configured to either step up orstep down the motor speed. It will additionally be appreciated that themotor 106 could be implemented as any one of numerous types of AC or DCmotors, but in a particular preferred embodiment the motor 106 isimplemented as a brushless DC motor.

As noted above, the motor 106 is selectively energized from the powerbus 115 under the control of the controller 108. The controller 108implements control logic via, for example, a central processing unit152. The control logic that the controller 108 implements duringoperation of the rotating machine may differ from the control logicimplemented during a shutdown sequence of the rotating machine. Forexample, during operation of the rotating machine the control logic mayimplement a predefined schedule of lubricant supply pressure as afunction of various conditions. More specifically, the controller 108may receive signals representative of various parameters. In response tothese signals, the control logic in the controller 108 may determine thescheduled lubricant supply pressure based on these parameters, andcontrol the motor 106 to rotate at least the supply pumps 118 at a speedthat will supply lubricant from the reservoir 102 at the scheduledlubricant supply pressure. Conversely, during the shutdown sequence, thecontrol logic may control the rotational speed of the motor 106 inaccordance with a schedule that will displace at least a substantialvolume of the lubricant in the rotating machine with air from thegaseous fluid source 126. Although the controller 108 is depicted usinga single function block, it is noted that the controller 108 may beimplemented as a single device or as two or more separate devices. Forexample, the controller 108 may implement the functions of both a motorcontroller and an engine (or other rotating machine) controller, or thecontroller 108 may be implemented separately, as a motor control unitand an engine control unit.

Regardless of the specific physical implementation of the controller108, and regardless of the specific control logic that is implemented inthe controller 108, when the shutdown sequence for the rotating machineis initiated, the system 100 is configured to de-lube the rotatingmachine. In the depicted embodiment, when the shutdown sequence isinitiated, a valve control signal is additionally supplied to thede-lube control valve 128 that causes the de-lube control valve 128 tomove to a position that fluidly communicates the supply pump inlets 117with the gaseous fluid source 126. It will be appreciated that thisvalve control signal may be supplied from the controller 108 or fromanother device. Preferably, however, the valve control signal issupplied from the controller 108. When the shutdown sequence isinitiated, a de-lube signal indicating that the rotating machine isbeing de-lubricated is additionally supplied to the controller 108. Thede-lube signal may be generated within the controller 108 or it may besupplied to the controller 108 from another device.

No matter the specific source of the de-lube signal, the controller 108,in response to the de-lube signal, controllably energizes the motor 106from the power bus 115. Because the supply pump inlets 117 are in fluidcommunication with the gaseous fluid source 126, air is discharged fromthe supply pumps 118 into the supply line 124. As alluded to above, thecontrol logic implemented by the controller 108 during the shutdownsequence controls the rotational speed of the motor 106 in accordancewith a schedule that will displace at least a substantial volume of thelubricant in the rotating machine with air from the gaseous fluid source126.

In addition to the above, the controller 108 is also responsive to thede-lube signal to cause the bypass control valve 146 to move to aposition that results in the fluid bypass line 144 remaining at leastsubstantially full of lubricant when the lubricant is displaced from thefluid supply line 124 and the rotating machine. The manner in which thecontroller 108 implements this functionality may vary, but in thedepicted embodiment the controller 108 supplies one or more signals thatresults in the bypass control valve 146 moving to the open position.With the bypass control valve 146 in the open position, the air beingdischarged by the pump will preferentially flow through the fluid supplyline 124 and into and through the rotating machine, rather than throughthe fluid bypass line 144. This will result in the lubricant beingdisplaced from the fluid supply line 124 and the rotating machine, yetthe fluid bypass line 144 will remain full, or at least substantiallyfull, of lubricant.

As was just noted, the controller 108 may cause the bypass control valve146 to open in accordance with any one of numerous implementations. Inone particular embodiment, the controller 108 supplies one or moresignals that directly or indirectly results in an increased flow rate ofthe fluid from the second fluid system 175 through the heat exchanger154. Because the flow rate of this fluid through the heat exchanger 154increases, the amount of heat transfer from the lubricant to the fluidalso increases, thereby cooling the lubricant in the fluid bypass line144. The increase in flow rate of the fluid from the second fluid system175 through the heat exchanger 154 is sufficient to maintain lubricanttemperature at the outlet of the bypass control valve 146 at or belowthe temperature at which the bypass control valve 146 will open.

It will be appreciated that in other embodiments, such as when thebypass control valve 146 is disposed in the fluid bypass line 144, thecontroller 108 will supply one or more signals that directly orindirectly cause the bypass control valve 146 to remain closed. It willadditionally be appreciated that for those embodiments in which thebypass control valve 146 is implemented with an electric, hydraulic, orpneumatic actuator, the controller could supply suitable signalsdirectly to the actuator that appropriately position the bypass controlvalve 146 to either prevent or inhibit air flow through the fluid bypassline 144 during the de-lubrication portion of the machine shutdownsequence.

The above-described process results in a portion of the lubricationsupply system 100 remaining full, or at least substantially full, oflubricant following the shutdown of the rotating machine. Hence, thelubricant fill volume during a subsequent start sequence of the rotatingmachine will be reduced relative to a system that is fully purged of itslubricant, and the lubricant pressure in the system 100 will riserelatively quicker. As a result, the electrical power drawn by the motor106 during the start sequence is significantly reduced relative to asystem that was fully purged of its lubricant.

While the invention has been described with reference to a preferredembodiment, it will be understood by those skilled in the art thatvarious changes may be made and equivalents may be substituted forelements thereof without departing from the scope of the invention. Inaddition, many modifications may be made to adapt to a particularsituation or material to the teachings of the invention withoutdeparting from the essential scope thereof. Therefore, it is intendedthat the invention not be limited to the particular embodiment disclosedas the best mode contemplated for carrying out this invention, but thatthe invention will include all embodiments falling within the scope ofthe appended claims.

1. An aircraft lubrication supply system, comprising: a motor coupled tobe selectively energized from a power bus and operable, upon beingenergized, to rotate at a rotational speed and supply a drive force; apump having at least a fluid inlet and a fluid outlet, the pump coupledto receive the drive force from the motor and configured, in responsethereto, to draw fluid into the fluid inlet from either a lubricantsource or a gaseous fluid source, and to discharge the fluid via thefluid outlet; a fluid supply line coupled to the fluid outlet andconfigured to supply the fluid discharged from the fluid outlet to arotating machine; a fluid bypass line having an inlet and an outlet, thefluid bypass line inlet coupled to the fluid supply line at a firstlocation, the fluid bypass line outlet coupled to the fluid supply lineat a second location that is downstream of the first location; a bypasscontrol valve disposed between the fluid bypass line inlet and the fluidbypass line outlet, the bypass control valve operable to control fluidflow at least through the fluid bypass line; and a controller configuredto couple to the power bus and to receive a machine de-lube signal, themachine de-lube signal indicating that the rotating machine is beingde-lubricated, the controller operable, upon receipt of the machinede-lube signal, to: (i) controllably energize the motor from the powerbus to thereby displace at least a substantial volume of lubricant inthe fluid supply line and the rotating machine with fluid from thegaseous fluid source, and (ii) cause the bypass control valve to move toa position that results in the fluid bypass line remaining at leastsubstantially full of lubricant when the at least substantial volume oflubricant is displaced from the fluid supply line and the rotatingmachine.
 2. The system of claim 1, wherein the bypass control valve isdisposed in the supply line between the first location and the secondlocation.
 3. The system of claim 1, wherein the bypass control valve isdisposed in the fluid bypass line between the bypass inlet and the fluidbypass line outlet.
 4. The system of claim 1, wherein the bypass controlvalve is responsive to fluid temperature to thereby control fluid flowat least through the fluid bypass line.
 5. The system of claim 1,further comprising: a heat exchanger coupled to receive fluid flowing inthe fluid bypass line and a second fluid flowing in a second fluidsystem at a flow rate, the heat exchanger configured to allow heattransfer between the fluid flowing in the bypass line and the secondfluid.
 6. The system of claim 5, wherein the controller, upon receipt ofthe machine de-lube signal, causes the flow rate of the second fluid tothe heat exchanger to vary.
 7. The system of claim 6, wherein thecontroller, upon receipt of the machine de-lube signal, causes the flowrate of the second fluid to the heat exchanger to increase.
 8. Thesystem of claim 1, further comprising: a de-lube control valve in fluidcommunication with the pump fluid inlet, the de-lube control valvemovable between at least a first position, in which the pump fluid inletis in fluid communication with the gaseous fluid source, and a secondposition, in which the pump fluid inlet is not in fluid communicationwith the gaseous fluid source.
 9. The system of claim 8, wherein thede-lube control valve is coupled to receive one or more de-lube valvecontrol signals and is operable, in response thereto, to move to eitherthe first or the second position.
 10. The system of claim 9, wherein thecontroller is further operable, in response to the de-lube signal, tosupply a valve control signal that causes the de-lube control valve tomove to the second position.
 11. An aircraft lubrication supply system,comprising: a motor coupled to be selectively energized from a power busand operable, upon being energized, to rotate at a rotational speed andsupply a drive force; a pump having at least a fluid inlet and a fluidoutlet, the pump coupled to receive the drive force from the motor andconfigured, in response thereto, to draw fluid into the fluid inlet fromeither a lubricant source or a gaseous fluid source, and to dischargethe fluid via the fluid outlet; a fluid supply line coupled to the fluidoutlet and configured to supply the fluid discharged from the fluidoutlet to a rotating machine; a fluid bypass line having an inlet and anoutlet, the fluid bypass line inlet coupled to the fluid supply line ata first location, the fluid bypass line outlet coupled to the fluidsupply line at a second location that is downstream of the firstlocation; a bypass control valve disposed in the fluid supply linebetween the first location and the second location, the bypass controlvalve responsive to fluid temperature to control fluid flow through thefluid bypass line; and a controller configured to couple to the powerbus and to receive a machine de-lube signal, the machine de-lube signalindicating that the rotating machine is being de-lubricated, thecontroller operable, upon receipt of the machine de-lube signal, to: (i)controllably energize the motor from the power bus to thereby displaceat least a substantial volume of lubricant in the fluid supply line andthe rotating machine with fluid from the gaseous fluid source, and (ii)cause the bypass control valve to move to a position that results in thefluid bypass line remaining at least substantially full of lubricantwhen the at least substantial volume of lubricant is displaced from thefluid supply line and the rotating machine.
 12. The system of claim 11,further comprising: a heat exchanger coupled to receive fluid flowing inthe fluid bypass line and a second fluid flowing in a second fluidsystem at a flow rate, the heat exchanger configured to allow heattransfer between the fluid flowing in the bypass line and the secondfluid.
 13. The system of claim 12, wherein the controller, upon receiptof the machine de-lube signal, causes the flow rate of the second fluidto the heat exchanger to vary.
 14. The system of claim 6, wherein thecontroller, upon receipt of the machine de-lube signal, causes the flowrate of the second fluid to the heat exchanger to increase.
 15. Thesystem of claim 1, further comprising: a de-lube control valve in fluidcommunication with the pump fluid inlet, the de-lube control valvemovable between at least a first position, in which the pump fluid inletis in fluid communication with the gaseous fluid source, and a secondposition, in which the pump fluid inlet is not in fluid communicationwith the gaseous fluid source.
 16. A method of removing lubricant from alubrication supply system and a rotating machine supplied with lubricantby the lubrication supply system, the method comprising the steps of:supplying a gaseous fluid to the lubrication supply system to displacethe lubricant; preferentially directing the gaseous fluid through afirst section of the lubrication supply system and to the rotatingmachine, and at least inhibiting the gaseous fluid from flowing througha second section of the lubrication supply system, whereby the gaseousfluid displaces the lubricant in the rotating machine and in the firstsection of the lubrication supply system, and the second section of thelubrication supply system remains at least substantially full oflubricant.
 17. The method of claim 16, wherein the lubrication supplysystem includes a control valve that, based on its position, selectivelyat least inhibits fluid flow through the second section of thelubrication supply system, and wherein the method further comprises:positioning the control valve to a position that at least inhibits fluidflow through the second section of the lubrication supply system. 18.The method of claim 16, wherein: the control valve is disposed in thefirst section of the lubrication supply system; and the step of positionthe control valve comprises positioning the control valve to an openposition.
 19. The method of claim 16, wherein the control valve isdisposed in the second section of the lubrication supply system; and thestep of position the control valve comprises positioning the controlvalve to a closed position.
 20. The method of claim 16, furthercomprising: disposing a heat exchanger in the second section of thelubrication supply system; flowing fluid in the second section of thelubrication system and a second fluid from a second fluid system throughthe heat exchanger; and increasing the flow of the second fluid throughthe heat exchanger.